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How To Linux Read Only User
Question: How do I make a Linux user read only?
› Verified 6 days ago
Linux + how to give only specific user to read the file
# chgrp tutu /home/grafh/file.txt [email protected]:
# chmod 640 /home/grafh/file.txt This file will remain owned by root , but be readable (but not writeable) by tutu and not by the other other users. linux read only file
› Verified 1 days ago
Create read only user and grant SSH access — Ask Ubuntu
› Verified 1 days ago
centos — How to create read only root type user in Linux
› Verified 2 days ago
How to give read-only permission for specific user for
› Verified 8 days ago
[SOLVED] Create read only user for all databases mariadb?
› Verified 6 days ago
How to manage Linux permissions for users, groups, and
› Verified Just Now
read only — How to create a readonly root linux: Can be
› Verified 9 days ago
To create user name with read only access — UNIX
› Verified 8 days ago
sql server — How to create a read-only user for a
› Verified 9 days ago
Oracle Read Only User
› Verified 3 days ago
How to fix Linux error «read-only file system» DUNTUK
› Verified Just Now
How to Change Permissions and Owners via Linux Command Line
› Verified 5 days ago
How I Give a User Permission to a Folder in Linux
› Verified 6 days ago
4.5. Setting User Permissions Red Hat Enterprise Linux 7
› Verified 4 days ago
How to Use the chmod Command on Linux
› Verified 1 days ago
Chmod Command in Linux (File Permissions) Linuxize
› Verified 9 days ago
Assign Read/Write Access to a User on Specific Directory
› Verified 9 days ago
Manage user accounts on your Amazon Linux instance
]$ mkdir .ssh [newuser
]$ chmod 700 .ssh Important Without these exact file permissions, the user will not be able to log in.
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File Permissions in Linux/Unix: How to Read/Write & Change?
Updated October 7, 2021
Linux is a clone of UNIX, the multi-user operating system which can be accessed by many users simultaneously. Linux can also be used in mainframes and servers without any modifications. But this raises security concerns as an unsolicited or malign user can corrupt, change or remove crucial data. For effective security, Linux divides authorization into 2 levels.
In this Linux file commands tutorial, you will learn-
The concept of Linux File permission and ownership is crucial in Linux. Here, we will explain Linux permissions and ownership and will discuss both of them. Let us start with the Ownership.
Click here if the video is not accessible
Ownership of Linux files
Every file and directory on your Unix/Linux system is assigned 3 types of owner, given below.
A user is the owner of the file. By default, the person who created a file becomes its owner. Hence, a user is also sometimes called an owner.
Group
A user- group can contain multiple users. All users belonging to a group will have the same Linux group permissions access to the file. Suppose you have a project where a number of people require access to a file. Instead of manually assigning permissions to each user, you could add all users to a group, and assign group permission to file such that only this group members and no one else can read or modify the files.
Other
Any other user who has access to a file. This person has neither created the file, nor he belongs to a usergroup who could own the file. Practically, it means everybody else. Hence, when you set the permission for others, it is also referred as set permissions for the world.
Now, the big question arises how does Linux distinguish between these three user types so that a user ‘A’ cannot affect a file which contains some other user ‘B’s’ vital information/data. It is like you do not want your colleague, who works on your Linux computer, to view your images. This is where Permissions set in, and they define user behavior.
Let us understand the Permission system on Linux.
Permissions
Every file and directory in your UNIX/Linux system has following 3 permissions defined for all the 3 owners discussed above.
- Read: This permission give you the authority to open and read a file. Read permission on a directory gives you the ability to lists its content.
- Write: The write permission gives you the authority to modify the contents of a file. The write permission on a directory gives you the authority to add, remove and rename files stored in the directory. Consider a scenario where you have to write permission on file but do not have write permission on the directory where the file is stored. You will be able to modify the file contents. But you will not be able to rename, move or remove the file from the directory.
- Execute: In Windows, an executable program usually has an extension “.exe” and which you can easily run. In Unix/Linux, you cannot run a program unless the execute permission is set. If the execute permission is not set, you might still be able to see/modify the program code(provided read & write permissions are set), but not run it.
File Permissions in Linux/Unix
Let’s see file permissions in Linux with examples:
ls – l on terminal gives
Here, we have highlighted ‘-rw-rw-r–‘and this weird looking code is the one that tells us about the Unix permissions given to the owner, user group and the world.
Here, the first ‘–‘ implies that we have selected a file.p>
Else, if it were a directory, d would have been shown.
The characters are pretty easy to remember.
r = read permission
w = write permission
x = execute permission
– = no permission
Let us look at it this way.
The first part of the code is ‘rw-‘. This suggests that the owner ‘Home’ can:
- Read the file
- Write or edit the file
- He cannot execute the file since the execute bit is set to ‘-‘.
By design, many Linux distributions like Fedora, CentOS, Ubuntu, etc. will add users to a group of the same group name as the user name. Thus, a user ‘tom’ is added to a group named ‘tom’.
The second part is ‘rw-‘. It for the user group ‘Home’ and group-members can:
- Read the file
- Write or edit the file
The third part is for the world which means any user. It says ‘r–‘. This means the user can only:
.png)
Changing file/directory permissions with ‘chmod’ command
Say you do not want your colleague to see your personal images. This can be achieved by changing file permissions.
We can use the ‘chmod’ command which stands for ‘change mode’. Using the command, we can set permissions (read, write, execute) on a file/directory for the owner, group and the world.
Syntax:
There are 2 ways to use the command –
- Absolute mode
- Symbolic mode
Absolute(Numeric) Mode
In this mode, file permissions are not represented as characters but a three-digit octal number.
The table below gives numbers for all for permissions types.
| Number | Permission Type | Symbol |
|---|---|---|
| 0 | No Permission | — |
| 1 | Execute | –x |
| 2 | Write | -w- |
| 3 | Execute + Write | -wx |
| 4 | Read | r– |
| 5 | Read + Execute | r-x |
| 6 | Read +Write | rw- |
| 7 | Read + Write +Execute | rwx |
Let’s see the chmod permissions command in action.
.png)
In the above-given terminal window, we have changed the permissions of the file ‘sample to ‘764’.
.png)
‘764’ absolute code says the following:
- Owner can read, write and execute
- Usergroup can read and write
- World can only read
This is shown as ‘-rwxrw-r–
This is how you can change user permissions in Linux on file by assigning an absolute number.
Symbolic Mode
In the Absolute mode, you change permissions for all 3 owners. In the symbolic mode, you can modify permissions of a specific owner. It makes use of mathematical symbols to modify the Unix file permissions.
| Operator | Description |
|---|---|
